1. Field of the Invention
The present invention relates to an optical modulator, an optical device having the optical modulator and a projector having the optical modulator or the optical device.
2. Description of Related Art
Conventionally, a three-plate projector having an optical device including a color separating optical system for separating a light beam irradiated by a light source lamp into three color lights of R, G and B using a dichroic mirror, three optical modulators such as liquid crystal panel for independently modulating the separated light beams in accordance with image information and an color synthesizing optical device such as a cross dichroic prism for synthesizing the light beams modulated by the liquid crystal panels has been known.
The optical device used for such three-plate projector is constructed by bonding and fixing the liquid crystal panel on the light-incident side of prism through a wedge-shaped spacer or a pin spacer (see Japanese Patent Laid-Open Publication No. Hei 11-160788 and Japanese Patent Laid-Open Publication No. 2003-121937). Since the liquid crystal panel of such optional device is directly bonded and fixed on the prism, there is no need for providing an independent support for the liquid crystal panel, so that the size of the projector can be greatly reduced.
In such optical device, an optical converter having a substrate with an optical conversion film such as polarization film and vision-angle correcting film has to be interposed between the light-incident side of the prism and the liquid crystal panel and both of the liquid crystal panel and the optical converter have to be efficiently cooled.
Accordingly, an arrangement has been proposed, where a base made of heat-conductive material such as metal is bonded on at least one of the sides intersecting a plurality of light-incident sides of the prism and the heat generated on the optical converter and the liquid crystal panel is absorbed by the base which is forcibly cooled, thereby efficiently cooling the optical converter and the liquid crystal panel.
However, since the optical converter is bonded on the base and the liquid crystal panel is bonded and fixed thereon through a spacer, when there is difference between the heating condition of the optical converter or the liquid crystal panel, the heat is transferred to one of the optical converter and the liquid crystal panel to the other, so that both of the components cannot be efficiently cooled.
Further, in such arrangement where the optical modulator such as liquid crystal panel ia bonded and fixed on the optical converter through a spacer, since sufficient gap cannot be retained between the light-incident side of the prism and the liquid crystal panel, cooling efficiency may be deteriorated.